N erve B locks for Chronic P ain James Jarman FANZCA FFPMANZCA PG Cert US Anaesthetist and Pain Specialist Joondalup and SJOG Midland Hospitals Perth Ultrasound Learning R esources ID: 929675
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Slide1
Ultrasound Guided Peripheral Nerve Blocks for Chronic Pain
James Jarman FANZCA, FFPMANZCA, PG Cert US
Anaesthetist and Pain Specialist
Joondalup
and SJOG Midland Hospitals, Perth
Slide2Ultrasound Learning ResourcesYOUTUBE IS YOUR FRIEND!Lots of great videos available on
youtube
Sonosite
have a great
youtube
channel
“Essential Anatomy” app – demonstration to follow
Slide3Slide4Slide5Ultrasound skills:US blocks are composed of 2 skillsIdentifying the nervesManipulating the needle
Identifying nerves
:
KNOW YOUR ANATOMY
Practice scanning yourself
Nerves frequently run with arteries – look for an artery and nerve if often nearby-
eg
ilioinguinal
, adductor canal, SSNB, popliteal
tibial
.
Nerves also tend to run in
fascial
planes – if you get your LA into the right plane it will usually work
Proximal nerves are mostly “nerve” (=fat=black) with little white connective tissue. As you move distally and branches are given off, nerves become a more speckled white colour due to higher proportion of connective tissue. Proximal nerves are more vulnerable to injury than distal nerves and blocks are associated with a higher risk of nerve injury
If unsure what you see is a nerve, scan proximally and distally- nerves will stay present, tendons and other things will tend to get bigger/ smaller/ disappear
If still unsure, stimulate the nerve
eg
50hz with RF needle (note RF needles can be very hard to see with US, especially for deep blocks
Slide6Right:
(Distal)
- Median
nerve (M)
in
forearm.
Little nerve, lots of white connective tissue
Left: (Proximal) brachial plexus (interscalene). Lots of
dark nerve, little connective tissue
Slide7Ultrasound skillsIdentifying nerves: Nerves vs vessels Arteries and pulsatile and incompressible
Veins are non pulsatile and compressible
Nerves and not pulsatile or compressible
Can also use colour
doppler
(NB red
vs
blue is flow away/ towards transducer)
Needle manipulation
:
can be practiced on gel phantoms or on chicken legs / breasts: can see nerves in
themPRACTICE!
Slide8Ultrasound technique In plane (LEFT) vs out of plane (RIGHT):
Slide9In plane vs out of planeIn plane vs out of plane:
I do all my blocks in plane
Allows you to see both the needle tip and the nerve and ensure no contact
With out of plane run risk of spearing the nerve
In plane does require more practice to perfect
Of needle and ultrasound beam in same plane can see a “false” tip of the needle: giveaway in that will not see the whole needle shaft- if not seeing whole shaft likely that beams aren’t
alligned
Only advance the needle when you can see the tip!
Slide10Technique: Hand-screen-handsCommon problem with ultrasound beginners is “screen fixation”: leads to needle plane and probe plane divergingCorrect eye movements is hands-screen-hands-screen
Slide11Tips: AnisotropyUlnar nerve at the forearm
Slide12Ultrasound and AnisotropyAnisotropy: As transducer is tilted backwards and forwards nerve can come in or out of view
Most
noticable
anisotropy: popliteal sciatic nerve:
As tilt probe backwards and forwards nerve appears and disappears
For this block, aiming beam a little towards patients head helps
Slide13Needle insertion point: close and steep or far and shallow?
Slide14US technique: needle insertion pointNeedle insertion site relative to probe: Close and steep vs far and shallowShort needle inserted next to probe= Steep angle = poor needle view BUT needle easier to control
Long needle inserted further away from probe= shallow angle and better needle view but hard needle to steer: need to pull right back to skin then re-angle. Also allows free movement and rearrangement of probe without bumping into needle
I broadly tend to use close and steep for shallow blocks (1-2 cm depth), an in-between position for medium depth and far and shallow for deeper blocks (>5cm)
Slide15Technique: Maximising screen real estate
Slide16Screen setupI position target at the edge of the screen not the middleMakes use of the whole screenCan always move the probe further away from the needle to see the rest, but can’t move the probe closer to the needle if it’s hitting it!
Allow whole path of needle to be seen
Forces flatter needle trajectory meaning better
visualisation
Slide17Equipment setupGet rid of any air in the syringe / needle / lineEven a tiny amount to air will destroy the ultrasound image and make the block impossible
Slide18Can’t see needle?Eg Suprascapular block on obese patient with RF needleTry small boluses of saline / dilute local anaesthetic to visualise
tip location
Slide19Slide20Saphenous blockSaphenous nerve supplies knee and strip of skin over medial calfRecent cadaver studies suggest may also provide some innervation to medial ankle joint
Can be blocked at adductor canal in mid thigh (US), by SC infiltration at level of
tibial
plateau or distally at ankle
Slide21Slide22Slide23Needle entry from Anterior-Lateral
Slide24Suprascapular nerve blockSo much easier than using IICan add pulsed RF fairly easily, or thermal (eg
in elderly who are not candidates for surgery)
Practical tips (just one way of doing it):
Sit patient in a chair (if not liable to faint). Can also be done prone.
Arm must
be hanging by side
: if arm is abducted acromion get in the way of the US probe
I use a 100mm block needle with block or RF needle if using RF. RF is hard to see on US. If using RF seek out the stimulation
In some patients
may need to angle the probe (heel-toe) laterally
to peek under the bone
Make sure you are looking lateral enough: most common failure to see the dip and ligament in not being lateral enough
Nerve very hard to see, as is artery: if can get it under the ligament it will workSeeing the ligament lift up is a very good sign
Slide25Slide26Slide27Slide28Slide29Slide30Rectus Sheath block for ACNES
Slide31Abdominal Cutaneous nerve entrapment syndromeEstimated incidence of 1:2000 or up to 25% of all undiagnosed chronic abdominal painVan Assen
,
Brouns
et al, Scan J Trauma 2015
Srinivasan
R,
Greenbaum
et al, Am J
Gastoent
2002;97:824-30
M
ore
common in womenPatients present with localised abdominal pain- can put their finger on the area of painTypically lies at lateral border of rectus muscleMay follow surgery / trauma – eg around laparoscopic port sites.Worse on contracting abdominal muscles (Carnett sign)Area of altered skin sensation around painful area (hyper/ hypoaesthesia)RCT of 48 patients to lignocaine or saline injection showed 4/22 improved in saline group compared to 13/22 in lignocaine group at 2 week follow upBoelens OBA British Journal of Surgery 2012;99
Slide32Nerves run between IOM and Transversus abdominus, then posterior to rectus muscle before perforating through it to skin
Slide33Above (top) and below arcuate lineNB below arcuate line (5-10cm below umbilicus) is no fascial
sheath deep to rectus
abdominus
Slide34Slide35Slide36Lateral Femoral Cutaneous nerve block
Slide37Slide38Slide39Slide40Femoral Nerve blockNot commonly done for chronic painFairly well known block so only short mention of some reminders
Book first on list, use lignocaine as quads weakness means falls risk
Note
fascial
planes:
Nerve is NOT in same plane as femoral vessels
Nerve lies deep to fascia
iliaca
, while vessels lie superficial
Nerve is often difficult to see on ultrasound, while artery is easy to see
Therefore aim for needle tip to be lateral and deep relative to the artery to be in the correct plane
Slide41Slide42Slide43Slide44Ilioinguinal Block:US probe position
Slide45Ilioinguinal block
Slide46Slide47Slide48Block SafetyData from anaesthetic literature demonstrates very good safety profileIncidence of temporary nerve injury in region of 0.1-1% (more for proximal blocks and upper limb blocks). Small peripheral nerves (
eg
LFCN, ACNES)
are particularly low risk
Incidence of permanent nerve injury (>6months)
approx
1:10 000
Seizures
approx
1: 10 000
Slide49SummaryUltrasound allows direct visualisation of target nerves, as well as of structures to avoid (eg vessels)
Peripheral blocks are a very low risk strategy which can sometimes pay off with significant results
Particularly useful in patients who can not tolerate medications (
eg
elderly).